Accumulation and effects of metals in caged carp and resident roach along a metal pollution gradient.

Metal accumulation and effects on plasma Ca(2+), alanine transaminase (ALT) and fish condition factor were examined in caged carp (Cyprinus carpio) and resident roach (Rutilus rutilus) at four locations along the Grote Nete River system (Belgium). Cadmium and zinc accumulation were found in carp and roach, with highest concentrations at the most contaminated site (dissolved Cd: 1.82 microg/l, Zn: 967 microg/l). On the tissue level, highest cadmium concentrations were measured in kidneys of carp and roach, followed by gills, intestine and liver, while low concentrations were observed in carcass and muscle. For zinc, a similar pattern was observed (intestine>kidney>gills>liver>carcass>muscle). Comparison between species showed higher cadmium concentrations in feral roach, while zinc levels were lower, owing to the high zinc concentrations in control carp. Furthermore, comparison of metal concentrations between two sampling periods (2005 and 2000-2001) revealed a drastic decrease in cadmium concentration in gills, liver and muscle of roach, similar to the reduction in waterborne cadmium concentrations, while differences for zinc were much less pronounced. In addition to metal accumulation, increased metallothionein concentrations (approximately 2x) were found in carp and roach, while no metal-related effects were found on ALT, Ca(2+)or condition factor. However, negative effects on fish community structure, as assessed by the index of biotic integrity (IBI), were found along the pollution gradient and indicated long-term adverse effects of metal pollution.

Gene expression analysis of estrogenic compounds in the liver of common carp (Cyprinus carpio) using a custom cDNA microarray.

Exposure to a variety of compounds with estrogenic activity has been shown to interfere with normal developmental and reproductive processes in various vertebrate species. The aim of this study was to determine the transcriptional profile of the natural estrogen, 17 beta-estradiol, and three synthetic estrogenic compounds (4-nonylphenol, bisphenol A, ethinylestradiol) in the liver of common carp, using a custom cDNA microarray. For that purpose, fish were aqueously exposed to three concentrations of each chemical for 24 or 96 h. Microarray analysis revealed that a total of 185 different gene transcripts were differentially expressed following exposure to at least one of the estrogen(-like) concentrations. We were able to identify a common set of 28 gene fragments, whose expression was significantly modified in the same way by the three xenoestrogens and 17 beta-estradiol. Although several of these gene expression effects corroborated past literature data, we also discovered some novel target genes of (xeno)estrogen exposure, providing interesting insights into the molecular basis of estrogenic effects. In addition, each of the four compounds induced gene expression changes that were not, or only partially, shared by the other chemicals, suggesting that not all chemicals with estrogenic activity act alike. These results demonstrate the potential of our custom Cyprinus carpio microarray to detect common estrogen-like activity as well as to identify unique compound-associated effects of (estrogenic) endocrine disruptors in fish.

Evaluation of the toxicological effects of perfluorooctane sulfonic acid in the common carp (Cyprinus carpio).

In the present study we evaluated the toxicological effects of a scarcely documented environmental pollutant, perfluorooctane sulfonic acid (PFOS), on selected biochemical endpoints in the common carp, Cyprinus carpio. Juvenile organisms were exposed to PFOS through a single intraperitoneal injection (liver concentrations ranging from 16 to 864 ng/g after 5 days of exposure) and after 1 and 5 days effects were assessed in liver and serum of the exposed organisms. The investigation of the hepatotoxicity of PFOS included the determination of the peroxisome proliferating potential (peroxisomal palmitoyl CoA oxidase and catalase activity) and the compounds influence on the average DNA basepair length (ABPL) by agarose gel electrophoresis. Total antioxidant activity (TAA), cholesterol and triglyceride levels were monitored in the serum. After 1 day of exposure the ABPL was significantly increased in the 270 and 864 ng/g treatment groups. After 5 days of exposure significant increases relative to the control were observed for the 16, 270 and 864 ng/g treatment groups. Enzyme leakage from the liver was investigated by measurement of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in the serum. At 561, 670 and 864 ng/g PFOS a significant increase in serum ALT activity became apparent after 5 days of exposure with values ranging from 159 to 407% relative to the control. For serum AST activity a significant increase for the 864 ng/g treatment group was observed with a value of 112% relative to the control. Determination of the polymorphonuclear leukocyte migration into liver tissue as assessed through myeloperoxidase (MPO) activity in liver, was used as an indicator for inflammation. It appeared that inflammation was not involved in the observed membranous enzyme leakage for the 561, 670 and 864 ng/g PFOS treatment groups. The results of this study suggest that PFOS induces inflammation-independent enzyme leakage through liver cell membranes that might be related to cell necrosis. Furthermore, results show that PFOS does not significantly affects serum antioxidant levels nor does it clearly induce peroxisome proliferation in carp. This study also points out that PFOS might interfere with homeostasis of the DNA metabolism. The results of these biochemical analyses were used to perform an initial hazard assessment study indicating that PFOS levels observed in tissues of wildlife populations could induce a clear rise in serum transaminase levels indicative for disruption of hepatocyte membrane integrity.

The combined effects of hardness, pH, and dissolved organic carbon on the chronic toxicity of Zn to D. magna: development of a surface response model.

The effect of changes in pH, hardness, and dissolved organic carbon (DOC) and the possible interactions among these parameters on the chronic toxicity of zinc to D. magna were investigated. Based on a Central Composite Design, models were developed that can explain the observed variation in EC(10) and EC(50) as a function of these toxicity modifying factors. All three parameters significantly altered the observed effect concentrations based on net reproductive rate. The largest differences in 21-day EC(10)s and EC(50)s caused by these factors were 10.1 and 4.9, respectively. An increase in pH and/or DOC decreased zinc toxicity. The significant interaction between pH and DOC on observed chronic Zn toxicity is in accordance with earlier reported increased sorption efficiency of Zn to humic substances at higher pH levels. Lowest Zn toxicity was observed in tests performed with moderately hard test media (between 200 and 300 mg/L as CaCO(3)). Lower or higher hardness of the test medium resulted in lower effect concentrations. Based on physico-chemical characteristics of the test media, developed models can be used to explain the variation between reported NOECs for Zn and may improve current environmental risk assessment procedures of metals.

The use of biomarkers in Daphnia magna toxicity testing V. In vivo alterations in the carbohydrate metabolism of Daphnia magna exposed to sublethal concentrations of mercury and lindane.

Aspects of the carbohydrate metabolism of Daphnia magna exposed for 48 and 96 h to sublethal concentrations of mercury and lindane were investigated. General as well as toxicant-specific perturbations in the intermediary metabolism were observed. Both model toxicants caused an increase in glycolytic and hexose-monophosphate shunt activity. Mercury exposure increased lactate dehydrogenase and isocitrate activity (only after 96 h), while lindane exposure, on the contrary, inhibited the cellular lactate formation and increased the Krebs' cycle activity (only after 48 h). Daphnids exposed to sublethal mercury concentrations clearly exhibited increased glycogenolytic activity, while in lindane-exposed organisms mainly glycogen phosphorylase inhibition was detected. The short-term enzyme-based effect levels (48--96 h LOEC and EC(10) values) were compared with the effects on the population dynamics. This evaluation for both model toxicants suggests that threshold levels (LOEC or EC(10) values) based on pyruvate kinase activity after 48 and 96 h of exposure could be potential early warning signals for long-term effects. A set of enzymatic endpoints, based on the intermediary metabolism, is suggested to characterize the metabolic state of the daphnids.